This invention relates to an intramedullary intertrochanteric fracture fixation appliance and a removable fitting device for use therewith.
Intramedullary intertrochanteric fracture fixation devices are known which comprise an intramedullary rod having an angulated opening to receive a femoral neck screw which is sometimes provided in the form of a lag screw. The intramedullary rod is fitted in the intramedullary canal of the femur and the neck screw passes through an opening in the intramedullary rod, through the neck of the femur and into the head. With this kind of device it is possible to produce tension in the neck screw to pull the head and neck of the femur together and means can be provided to prevent the screw rotating both during this operation and in its final position. This can be provided by the provision of grooves in the neck screw into which a set screw can be located thus allowing the neck screw to slide but not rotate and when the procedure has been completed the set screw can be tightened up to hold the parts in a fixed position. Alternatively, some surgeons prefer to leave the set screw loose merely preventing rotation as required for the particular patient.
It is also known to provide a fitting device to assist in locating the various parts during the operation. Thus, the fitting device may be arranged to clamp to the upper end of the intramedullary rod and to provide a guide to enable a hole to be bored in the head of the femur to accept the neck screw. The guide can also remain in position to assist in guiding the compression screw it is being screwed into position. Such fitting while devices can also provide guides for drilling holes further down the femur to allow location screws to be passed through the lower end of the intramedullary rod to locate the intramedullary rod.
A disadvantage with the arrangement set forth above is that the fitting device has to be removed to allow the set screw, or other means to hold the neck screw in position, to be operated and there is a tendency for the neck screw to unthread or move longitudinally in the intramedullary rod while the fitting device is being removed and before the set screw can be inserted, and an object of the present invention is to provide such an intramedullary intertrochanteric fracture fixation appliance which has provision for carrying out the operation of locking the neck screw and avoiding its becoming loosened or moving during the operation.